The invention relates to a magnetic holding brake, which is especially employed for the actuation of valves in the oil and natural gas industry. Examples of such valves include gate valves, chokes, ball valves, blow-out-preventers (BOP) or other similar devices.
Each of these valves has at least one valve member, which is adjustable into an opened and a closed position. The respective valve member is adjusted between the opened and the closed position by an adjusting part of the actuator. An electric motor of the actuator adjusts the adjusting part of the actuator via a corresponding drive shaft or motor shaft.
In the field of the oil and natural gas industry, valves are required to fulfill certain safety requirements, which may require that the electrically actuated valves maintain a certain position of the valve member during an energy failure.
One safety mode is called “fail safe close” or “fail safe open” and another safety mode is called “fail as is”. In the “fail safe close/open”-mode, the respective valve member of the valve is automatically driven to the closed or opened position during an energy failure. In the “fail as is”-mode, corresponding valve members of the valve remain in their currently assumed position during an energy failure.
In the “fail as is”-mode it is further to be considered that the valve member should be held in the opened or actuated position without the use of energy if possible.